1. Field of the Invention
The present invention relates to fluidic mixing devices and more particularly to an elongate mixing device used in conjunction with a fluid dispensing gun.
In many manufacturing processes it is necessary to completely mix and blend particulate solids, liquids or gases. However, a problem is presented when it is desired to mix materials having different viscosities, especially those materials having high viscosities which diffuse slowly. For instance, in the wood products industry and more particularly in plywood manufacturing, it is necessary to fill knotholes or other imperfections in plywood panels with a mix of resin and catalyst. It is imperative that the resin and catalyst be completely mixed before being used as a knothole or wood defect filler.
Furthermore, it is necessary in the plywood manufacturing industry to use a mixing device which may be readily disassembled and cleaned due to the fact that resin and catalyst set up or harden very quickly. If a mixing device is not flushed with a solvent after discharge of the resin and catalyst, residue may harden and prevent further discharge through the device. Thus, it becomes necessary that the fluidic mixer must be constructed of components easily disassembled.
2. Description of the Prior Art
A static mixing device is disclosed in U.S. Pat. No. 3,865,352. A mixing tube for mixing a plurality of fluids during their passage through the tube contains a hollow tube packed with shaped pieces, each of the pieces having a disk having at least one projection perpendicularly attached thereto. It is necessary that a plurality of shaped pieces be packed into the tube and it is readily apparent that some difficulty would be experienced in removing the shaped pieces if they became lodged within the tube due to hardening of mixed mterials. Also, it is apparent that a shaped piece could possibly work its way to an outlet nozzle of the tube to inadvertently plug up the nozzle. It is to be appreciated that applicant's invention utilizes a one-piece spiral rod which may be readily removed from a tube and which further will not impede flow through a discharge nozzle.
While not describing a mixing device per se, U.S. Pat. No. 2,020,194 discloses an arrangement for producing a helical flow of flue gases within a tube by providing an extended helical guide member within a pipe. The height of the helical guide member may be smaller than the radius of the pipe cross-sectional area and permits a flue gas traveling down the pipe to move somewhat in a whirl. However, it is to be noted that such a helical device would not adequately mix fluidic components because the helix is wound in a manner to provide an open region extending the length of the tube substantially in the middle of the helix. Thus, it becomes apparent that if fluidic components were introduced into one end of the tube, portions of the components could travel down the open region extending along the length of the tube and not be subjected to mixing agitation.
A static type foam mixing head to provide a polyurethane foam is set forth in U.S. Pat. No. 3,361,412. Here, a body member having a central chamber is provided in which a series of baffle structures permit expansion of foam before the foam issues from the outlet of the tube. It is to be noted that the baffle structures are generally circular in cross section and do not premit for passage of fluidic components along their outer peripheries between the inside diameter of the tube.
Further examples of mixing devices are described in U.S. Pat. No. 3,286,992 and 3,664,638. Both of these mixing devices employ a tube in which are disposed a plurality of serially arranged curved elements, each constructed of a thin flat sheet having a width approximately equaling the inner diameter of the tube and each having a length preferably 1.25 to several times its width. Each of the curved elements is twisted so that its upstream and downstream edges are substantially flat and arc at a substantial angle to each other.